res
to 0 (to count insertions) and right
to 0 (to count the number of right parentheses needed).c
in the string s
.
c
is '(', check if right
is odd. If so, decrement right
and increment res
.right
by 2, anticipating two ')' for each '('.c
is ')', decrement right
.right
is negative after decrementing, increment right
by 2 and res
by 1.right
to res
to account for any remaining unbalanced parentheses.res
as the minimum number of insertions needed.